Subwoofer insight.

Am I the only one that thinks this system is underpowered?  86dB 1w/1M on a 75W tube amp in a big space does not sound correct to me; I'd pick a good 200W/ch amp and see how that does.  I may agree with some of the sub comments, but you don't even have your main speakers set up right yet.  You won't know how the speaker really sounds until they are properly powered.

Underpowering speakers is the #1 most detrimental thing you can do to a speaker.  Running very long speaker cable runs is another, as those long cables suck all your power away and drastically decrease dampening factor so you get very poor bass performance.   so with a  75W amp, you don't have much room for error.  Try your speakers on a 1 foot length of 12 gauge OFC and see what happens.  Then borrow someone's big amp and try that, using your integrated as a preamp.  I bet its night and day. 

I work with speakers and amps all the time and I know from the ATC SCM19s i import, putting them on a small amp (say like a modern receiver, Denon, Yamaha, etc) they sound good.  Plenty of folks would be happy.  Put them on preamp with a big 200W or 300W amp (even if its a new Yamaha or Rotel or NAD -something like that) they sound like a different speaker- amazing!  Way more bass, way more dynamics, headroom etc.  If I tried that first, I might not add a sub.       

Brad

These low frequencies are inherent in the acoustic resonance of large spaces. Therefore present in all music that is well recorded in a large space.

Nonsense! It’s only present if the material was not filtered, which was often SOP for records. Any or all of the microphone, input channel, mix output, cutter could have been filtered to make the disk more playable.

OTOH, some unfiltered large space recording have enough sub-audible low end to put a plate amp sub into thermal shutdown. Adding a 12v 100 or 120mm computer fan run on ≈3.5vdc will keep the amp cool and dramatically extend its life.
see http://ielogical.com/assets/WinterBlues/Force_Fan.jpg Airflow is toward plate to force air up the channels.
The fan is held in place with the compliant mounting plugs. Even Saving Private Ryan or Telarc 1812 w cannon won’t shake it loose.

ricred1

I don’t listen to any music that has bass any where near 20hz, let alone below 20hz.

millercarbonThese low frequencies are inherent in the acoustic resonance of large spaces.

Huh? You must be hearing things!
I suggest you try and measure this "inherent" acoustic resonance. Feel free to report back with your findings.

Thanks Brad, easier said than done. I have often said to myself the same question. I know no one whom participates in these activities so borrowing is not an immediate option. Sure, I could make a local effort and see what is available but that is not who I am. Sure, I could use more power and more efficient speakers. To my ears the sound is quite pleasing. I’m sure I could hook something else up and be hooked. I don’t plan on that until I have to since quite happy with what I have. Just trying to optimize what I have.  Wasn’t looking to redo my system.  As said earlier, you only know what you know. Knowing more does not necessarily make life less complicated. In this situation, it actually makes it more complicated. Today, I listened to a DMB vinyl box set (1998) I bought for my wife as a present and just loved it with subs on rather than off. I don’t need perfection. Listening to it on my system sounds 99 percent better than anything else I have ever heard. Not saying 99 percent better than what everyone here has. Far from. Just saying 99 percent better than “The best of what’s around”!

ATC SCM19 has a published spec of
Frequency Response (-6dB): 54Hz-22kHz
Even 1000w is never going to get low end from it or any similar 2-way.

Power requirements fall approximately 50% per octave. Using the SCM19 as an example and rolling the bass @ 80Hz requires an amplifier of only 50w vs 200w full range. The smallish woofer is relieved and more easily accomplishes its task as a mid -bass & -range driver. There is no free lunch and no 6" driver is ever going to have the same output at 20Hz or even 40Hz as at 200Hz or 2kHz in any box of reasonable size.

A purpose built sub with 300w RMS peak has double the power necessary for the 20-80Hz range as the 50 for 80-20kHz. Something in the 10-12" range with similar sonics to the mains & properly set up will add musical realism beyond any amount of power.

IMO, unless one has completely separate HT & music systems, one should opt for musical sub[s]